Throughput Analysis for Parallel ARQ over Correlated MIMO Channels

We treat the throughput analyses of parallel ARQ schemes over correlated MIMO channels with adaptive modulation and coding (AMC). To describe the packet transmission over multiple parallel logic channels, we extend the existing burst- error model for single channel to multiple parallel logic channels. Based on such a packet error model, we derive the throughput of different parallel ARQ protocols. Moreover, to describe the temporally correlated physical channel fading, we generalize the existing Markov model for single channel to multiple parallel channels for MIMO systems. Then we develop a method for calculating the packet-level model parameters from the parameters of the physical-layer model and the MIMO transceiver. Using the above hierarchical throughput analysis framework, we investigate the potential throughput gain or throughput loss of parallel ARQ over the conventional serial ARQ in MIMO systems. Our results reveal that as SNR increases, parallel ARQ can achieve higher throughput gain or less throughput loss compared to serial ARQ; parallel SW can achieve throughput gain in most of the MIMO scenarios but increasing the number of antennas does not always bring higher gain; parallel GBN with large number of antennas and independent buffers can achieve throughput gain; parallel SR incurs throughput loss.